Interested to Buy Any Domain ? << Click Here >> for more details...
why motor starting current is High ?
- 11 Answers
- 25112 Views
- Bhel, Jindal, I also Faced
- E-Mail Answers
Answer Posted / guest
When voltage is first applied to the motor field winding, only the conductor resistance opposes the flow of current to the motor winding. For example a motor winding rated at 240V with a winding resistance of 0.6 ohms. Using Ohms law we find I (current)= E/R or 240V/0.6 ohms = 400Amps.
DURING MOTOR STARTING = LOW RESISTANCE, HIGH CURRENT
Because the conductor resistance is so low, the motor has a very large inrush current.
Once the rotor begins turning, the rotor bars (winding) are increasingly cut by the stationary magnetic field, resulting in increasing counter electromotive force (CEMF).
CEMF opposes the applied voltage, resulting in an increased opposition to current flow within the conductor, which is also called inductive reactance.
The increase in inductive reactance, because of self induction, causes the impedance of the conductor winding to increase and this results to reduced current flow.
Same motor, R=0.6 ohm, XL=6 ohms, V=240 volts
Z = √(R^2+〖XL〗^2 ) = √(〖0.6〗^2+6^2 ) = 6 ohms
I = E/Z = 240V/6Ω = 40Amps
DURING MOTOR RUNNING = LOW RESISTANCE, HIGH INDUCTANCE, LOW CURRENT
| Is This Answer Correct ? | 1 Yes | 0 No |
Post New Answer View All Answers
Draw torque - speed curve and load curve of induction motor? mark operating point ?
i m electrical diploma holder i want to do plc $ Scada some body tell me which insitute is best for me near chandigarh
what is a types of short circuit and what is a types of distance protection tests
by what factor the starting current is used when comparing star and delta connection for motor starting?
if there is nutral in phase why we use earthing wire and grounding? even at fault condition the fault current flows to neutral (it is a lower path)
Give details of your interested designation, the post you are interested to serve the company better and explain why you think you can serve the company better in such position if employed?
What is electrical diversity factor in electrical installations?
can we synchronize star system generators with delta system generators?
what is the difference between oil surge relay and buchholz relay.
what is the difference between pvc & fiber glass cables
How to control motor gearbox speed and friquency? If length of cable and dia given, how to measure the voltage drop?
1.what is the funtion of chiller primary & scondary pumps. 2.what is the use of distribution lines & Types. 3.what is the use the thermal power stations & how much capacity.
will there be any problem by recovering slip from single phase induction motors?
I need the recommended size for a 3 phase transformer at 13.8 KV Primary and connected loads of 3000 kVA at 4200 volts and 2375 kVA @ 480 volts AC.
Difference between rating factor of cable and derating factor of cable?
